1. Field of the Invention
This invention relates to a concrete product, more particularly to a concrete product which includes artificial sludge aggregates made from sludge, and a method of making the same.
2. Description of the Related Art
Currently, coals burnt in a thermal power plant produce many by-products, such as lightweight inflammable matters and a small amount of unburned carbon. These by-products flow together with exhaust gas, during the burning process, through a furnace chamber, a superheater, an economizer, and an air preheater where the by-products are cooled to about 35° C. These by-products are caught by the static electric dust collecting device as fly ash. The grain size of the fly ash is mostly smaller than 20 μm. The fly ash generally includes SiO2, Al2O3, and Fe2O3. The fly ash has a pH value ranging from 5.2 to 7.4.
Recycling of the fly ash is used in the making of tiles, ceramics, structural lightweight aggregates, foamed concrete blocks, fertilizers, and artificial reef armor blocks. Present statistics reveals that the annual production of the fly ash amounted to approximately 1.2 million tons, and the rate of use thereof is only 58.6%. The unused fly ash is thrown away and is directly buried on the ground. This destroys the soil, the mountains, and the streams. Hence, the problem of re-treating and recycling the fly ash still remains to be solved.
Further, furnace slag is a by-product produced in iron-smelting, and may be divided into two kinds according to the method of production, i.e., air-cooled slag and water-quenched slag. Generally, in the production of one ton of pig iron, 0.3 ton of the furnace slag is produced therealong. Air-cooled slag is usually treated as trash, as a graded material for backfilling the sea, or as a backfill in the factory area. The water-quenched slag has a property close to that of the cement, and is usually used as a cement additive for concrete mineral filler. Thus, if the furnace slag is thrown into the trash and is not reused, it will become a new problem to the environment.